C a s e r e P o r t food-dependent Cushing’s syndrome C. Messidoro1, J.W.F. Elte1*, M. Castro Cabezas1, M. van Agteren1,2, A. Lacroix3, W.W. de Herder2 1Department of Internal Medicine, Sint Franciscus Gasthuis, Rotterdam, the Netherlands, 2Department of Internal Medicine, Erasmus MC, Rotterdam, the Netherlands, 3Laboratory of Endocrine Pathophysiology, Department of Medicine, Centre Hospitalier de l’Université de Montréal (CHUM), Montréal, Quebec, Canada, *corresponding author: tel.: +31 (0)10-704 01 15, e-mail: [email protected] a b s t r a C t it has recently been proposed that other hormones than polypeptide (GIP) via binding to ectopic receptors on aCtH can control cortisol production in Cushing’s adrenal cells.2 syndrome with bilateral adrenal hyperplasia. We present We report a new case of bilateral adrenal enlargement a case of food-dependent Cushing’s syndrome. after a based on food-dependent Cushing’s syndrome, a less positive response of cortisol production during mixed known variant of Cushing’s syndrome. meals, several tests identified glucose-dependent insulinotropic polypeptide (GiP) as the driving hormone responsible for the cortisol overproduction. identification C a s e r e P o r t of aberrant hormone receptor expression is of importance because it may create a possibility for pharmacological A 57-year-old woman was referred to our outpatient treatment. clinic because of accidentally discovered bilateral adrenal enlargement. She complained of weight gain, abdominal discomfort, easy bruising, trembling and palpitations. K e y W o r d s No muscle weakness or psychological problems, such as depression, were reported. Physical examination ACTH-independent macronodular adrenal hyperplasia revealed hypertension (160/100 mmHg), centripetal fat (AIMAH), food-dependent Cushing’s syndrome, glucose- distribution without signs of muscle atrophy and ankle dependent insulinotropic polypeptide (GIP) oedema. No moon face or buffalo hump were noticed. The early morning fasting plasma cortisol level could not be suppressed (323 nmol/l; reference value <50 nmol/l) by i n t r o d uc t i o n 1 mg dexamethasone administered the previous evening. The 24-hour urinary free cortisol excretion was also Cushing’s syndrome is usually caused by excessive elevated (539 nmol/24 hours; reference values 30 to 150 ACTH secretion, such as in pituitary adenomas (as in nmol/24 hours). ACTH levels were below the detection Cushing’s disease) and ectopic ACTH secretion (as in limit (<10 ng/l) at all times. Further investigations showed small cell lung carcinomas and carcinoids); less frequently that the patient’s 24-hour urinary free cortisol excretion it is ACTH-independent, frequently caused by cortisol- appeared to be lower (444 nmol/l) during a fasting day as producing adrenal adenomas or carcinomas. However, compared with values on non-fasting days (539 nmol/l). ACTH-independent bilateral adrenal hyperplasia has also Plasma cortisol levels increased after mixed meals and been described. Adrenocortical cells then have the capacity decreased during fasting. Prolonged fasting was associated to secrete cortisol in the absence of detectable ACTH levels. with a progressive decrease in serum cortisol levels (figure In recent years, the presence of aberrant hormone receptors 1). Food-dependent Cushing’s syndrome was suspected. on adrenal cells of patients with ACTH-independent On intravenous infusion of GIP (0.6 µg/kg, while fasting) Cushing’s syndrome has been demonstrated.1 Hormones the plasma cortisol level more than doubled already or peptides other than ACTH control cortisol secretion in 15 minutes after infusion (figure 2). The response of these cases, for example glucose-dependent insulinotropic cortisol to ACTH administration (250 µg) was similar and © 2009 Van Zuiden Communications B.V. All rights reserved. may 2009, Vol. 67, No. 5 187 figure 1. Plasma cortisol levels while fasting ( ) and figure 3. Plasma cortisol levels during food intake ( ) during normal food intake ( ) and during treatment with octreotide pre-meals ( ) 700 700 600 600 500 500 400 400 300 Plasma cortisol levels (nmol/l) Plasma cortisol levels (nmol/l) 300 200 Meal Meal Meal 100 200 6 8 10 12 14 16 18 20 22 24 7 9 11 13 15 17 19 21 23 Time (hours) Time (hours) figure 2. Effect of a single infusion of GIP (0.6 µg/kg According to our experience and that of others reported body weight) on plasma cortisol levels in the literature,3,4 octreotide therapy only results in short-term suppression of the hypercortisolism. It 1000 was, therefore, decided not to treat the patient with octreotide. She subsequently underwent laparoscopic 900 bilateral adrenalectomy. The left adrenal tissue weighed 11 grams and the right adrenal lesion weighed 120 grams. 800 Both lesions were categorised as benign adrenocortical adenomas. 700 Total RNA was extracted from adrenals using Trizol 600 (Invitrogen). Multiplex RT-PCR using QuantumRNA 18S rRNA as an endogenous control (Spencer & Christensen 500 1999) was performed according to recommendations Plasma cortisol levels (nmol/l) by the manufacturer, as follows: the RT-PCR reaction 400 was terminated when all samples were in the linear GIP 0.6 µg/kg body weight range of amplification. For each gene, seven RT-PCR 300 reactions with a pool of cDNA from normal adrenals -30 0 30 60 90 120 150 180 210 240 270 were performed using the specific primers, submitted Time (minutes) before and after GIP infusion to PCR and one tube was removed every four cycles, starting from the 12th cycle; then, all the PCR products were resolved in ethidium bromide stained 1.5% agarose gel, detected by Typhoon and quantified by ImageQuant. Cycle number was plotted against the log of the signal and served as a reference test (data not shown). This proved a straight line was obtained for samples in linear range of food-dependent Cushing’s syndrome in this patient. amplification; the medium point was chosen. Multiplex A posture test was performed to screen for receptors to PCR using two sets of primers, one to amplify the angiotensin II, vasopressin and catecholamines and the cDNA of interest and a second to amplify an endogenous tests were negative. control (18S rRNA - QuantumRNA 18S Internal Standards, Octreotide treatment before meals (0.1 mg subcutaneously Ambion Inc. Austin-Texas, USA), was performed. The 3 times/day) reduced plasma cortisol levels (figure 3). product level of the gene of interest was normalised Urinary cortisol excretion was 414 nmol/l, lower than against the product from the control reaction. The PCR the other values (in the fasting or the non-fasting state). reactions contained 10 mM Tris-HCl (pH 8.3), 1.5 mM Messidoro, et al. Food-dependent Cushing’s syndrome. may 2009, Vol. 67, No. 5 188 MgCl2, 50 mM KCl, 0.2 mM each of deoxy-dNTP, 20 or hormone released after meals, instead of ACTH. All pmol each of sense and anti-sense primers specific for healthy persons produce GIP from endocrine K cells in the the gene of interest, 2 µl of RT reaction, 2.5 U Taq small intestine (duodenum and proximal jejunum) after DNA polymerase and 2 µl of 18S PCR Primer Pair.5 oral food intake.6 This release increases with higher fat GIP receptor was found to be over-expressed on the adrenal and carbohydrate intake and decreases with protein intake. tumour cells as compared with a normal adrenal or normal GIP has a positive effect on the release and synthesis of human pancreas (figure 4). insulin, thus its name: glucose-dependent insulinotropic She gained weight in the first year postoperatively, and polypeptide. then lost a total of 3 kg. The hypertension resolved. The patient developed type 2 diabetes five years postoperatively, In patients with food-dependent Cushing’s syndrome, which is now well controlled with oral glucose-lowering GIP is released in physiological concentrations in the drugs. small intestine; however, because of the binding to the ectopic or overexpressed adrenal GIP receptors this results in a postprandial increase in plasma cortisol. Cortisol figure 4. GIP receptor expression in control pancreas, exerts its negative feedback on ACTH and CRH synthesis control adrenal and in 5 cases of GIP-dependent and leads to suppressed levels of plasma ACTH and adrenal AIMAH with Cushing’s syndrome thereby to low fasting cortisol levels. In some patients with GIP-dependent Cushing’s syndrome, plasma cortisol levels are not as low, possibly as the result of the expression of more than one aberrant receptor. In this case report it was remarkable that in the fasting state cortisol levels also increased around the meal times relative quantitative RT-PCr products in agarose gel, showing the (morning and evening). This could be a result of the two GiPr isoforms (545 and 456 bp) and the internal control r18s presence of other aberrant receptors, but this has not been (324bp). sample in lane 3 with the asterisk is the patient reported in this study. tested. In addition, no cortisol increase was found after lunch during feeding and fasting; this could be due to a bigger contribution of physiological morning and evening increases in cortisol than the result of the influence of GIP. d i s cu s s i o n The investigators did not screen for all possible receptors such as the glucagon receptor and the serotonin In recent years, new aetiologies of ACTH-independent (5-HT4) receptor; a posture test was performed unilateral and bilateral adrenal hyperplasia have been to screen for receptors to angiotensin II, vasopressin added to the spectrum of ACTH-independent Cushing’s and catecholamines; these tests were negative. The syndrome. presence of other aberrant receptors could, however, It has been established that the aberrant stimulation of have influenced the cortisol pattern in this patient.